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2 Ionization energyThe energy needed to remove an electron completely from at atom.Depends upon ….The attraction between the positively charged nucleus and the negatively charged electron.The repulsion between the negatively charged electrons.

32 The second energy level must be subdivided into two sublevels each with a different energy.The fifth electron for boron must be in a higher energy level because it takes less additional energy to remove it.

33 Electrons in the higher sublevelThe second energy level must be subdivided into two sublevels each with a different energy.The fifth electron for boron must be in a higher energy level because it takes less additional energy to remove it.Electrons in the lower sublevel

34 Electrons in the higher sublevelThe same is true for the third energy level.Electrons in the lower sublevel

35 There are many limitations of the Bohr model, including the fact that the calculations work only for hydrogen.But there is one overriding reason why the Bohr model is so important to our study of the atom and the arrangement of electrons.The Bohr model tells us that electrons are located only in certain, discrete energy levels and that they can only change from one energy level to another by gaining or losing energy.

36 The Bohr model has a few discrete energy levels.4An “excited electron” is located in one of these energy levels32A ground-state electron is located in the lowest energy level.1

37 n2n2128318432550The number of electrons in the nth energy level is given by 2n2.The Bohr model showed only 8 electrons in the third energy level. Where are the other ten electrons?

38 The Quantum mechanical model has more energy levels available to electronsn is the “principle quantum number, one of 4 numbers that uniquiely describe each electron in an atom4n2n21283184325503Except for the first energy level, each energy level in the Bohr model is “subdivided” into two or more “sublevels.”21

39 In multi-electron atoms the original Bohr energy levels are split into sublevels.4n2n2128318432550321

40 In multi-electron atoms the original Bohr energy levels are split into sublevels.4n2n2128318432550321

41 Overlap between energy sublevels.In multi-electron atoms the original Bohr energy levels are split into sublevels.4Overlap between energy sublevels.n2n2128318432550321

42 The letters s, p, d and f are used to label the sublevels.In multi-electron atoms the original Bohr energy levels are split into sublevels.The letters s, p, d and f are used to label the sublevels.4f4d44pn2n21283184325503d4s33p3ss = sharpp = principled = diffusedf = fundamental2p22s11s

43 The letters s, p, d and f are used to label the sublevels.In multi-electron atoms the original Bohr energy levels are split into sublevels.The letters s, p, d and f are used to label the sublevels.4f4d4324pn2n21283184325503d4s33p18sublevelnumber of electronss2p6d10f143s2p282s211s

45 Since we can’t see atoms or the electrons we have no idea what they actually look like. Yet we need a way to represent the organization of electrons in an atom.Much like technicians use a schematic diagram to represent the components in an electronic circuit, chemists use the electron energy diagram to represent electrons in an atom.

46 Much like technicians use a schematic diagram to represent the components in an electronic circuit, chemists use the electron energy diagram to represent electrons in an atom.

47 1s2s2p3s4s3p4p3d4d5s5p6s4f5d6p7s5f6d7pE n e r g yElectron Energy DiagramThe electron energy diagram is a schematic diagram representing the arrangement of electrons in an atom.It consists of lines representing the orbitals in the various energy sublevels.n2n2128318432550s2p6d10f14

48 1s2s2p3s4s3p4p3d4d5s5p6s4f5d6p7s5f6d7pE n e r g yElectron Energy DiagramEach of the lines represents an “orbital” where up to two electrons can be located.n2n2128318432550s2p6d10f14

49 An orbital is a “region in space” within an atom where up to two electrons can be located.An s-orbital is spherical. Two electrons.The p-orbitals are “dumbell” shaped. Each orbital contains two electrons, for a total of sixThe Shrodinger wave equation predicts the shape of the orbitals.

50 The five d-orbitals are shaped like thisThe five d-orbitals are shaped like this. Each orbital can contain two electrons, for a total of 10 electrons. The transition metals are filling the d-orbitals.

51 Electron Energy Diagram for ArsenicEach horizontal line represents an orbital, a region which can be occupied by up to two electrons.1s2s2p3s4s3p4p3d4d5s5pE n e r g yElectrons with opposite spin are represented by up and down arrows.The electron energy diagram represents the arrangement of the electrons in their respective energy levels and sublevels.

54 Electron Energy DiagramThe second energy splits into two sublevels called “s” and “p”. An s-sublevel holds two electons. A p-sublevel holds up to six electrons in three orbitals.2p2s1s

55 Electron Energy DiagramThe third energy splits into three sublevels, the “s”, the “p”, and the “d”. The d-sublevel holds up to ten electrons in five orbitals.E n e r g y3d3p3s2p2s1s

56 Electron Energy DiagramNotice that the 4s sublevel is lower in energy than the 3d sublevel.4fE n e r g yThe fourth energy splits into four sublevels, the “s”, the “p”, the “d”, and the “f ”. The f-sublevel holds up to 14 electrons in seven orbitals.4d4p3d4s3p3s2p2s1s

57 Electron Energy Diagram5f5d4fE n e r g y5pNotice the overlap again in the 5s and 4d, and the location of the 4f sublevel.4d5s4p3d4s3p3s2p2s1s

110 1s2, 2s2 2p6, 3s2 3p6, 4s2 4p3 Electron Energy Diagram for ArsenicWe can simplify the “electron configuration” even more by using the “inert gas core” to represent the electrons which do not take part in chemical reactions.E n e r g y1s2, 2s2 2p6, 3s2 3p6, 4s2 4p3

111 Ar 4s2 4p3 Electron Energy Diagram for ArsenicWe can simplify the “electron configuration” even more by using the “inert gas core” to represent the electrons which do not take part in chemical reactions.E n e r g yAr 4s2 4p3